System for controlling vibration of a dynamic surface

ABSTRACT

A system for controlling vibration of a dynamic surface includes at least one sensor in communication with the dynamic surface for measuring vibration of the dynamic surface and generating a feedback signal proportional to the measured vibration and at least one piezoelectric actuator in communication with the dynamic surface and in communication with the controller for receiving the output signal. The system also includes at least one mass overlying the at least one piezoelectric actuator, whereby the at least one piezoelectric actuator lies between the mass and the dynamic surface, and a controller in communication with the at least one sensor for receiving the feedback signal, generating an output signal in response to the feedback signal and sending the output signal to the at least one piezoelectric actuator. The piezoelectric actuator applies a counter force between the dynamic surface and the mass upon receiving the output signal for reducing or controlling vibration of the dynamic surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of commonly assigned U.S.patent application Ser. No. 09/425,594 filed Oct. 22, 1999, entitled“System and Method for Controlling Deflection of a Dynamic Surface”, thedisclosure of which is hereby incorporated by reference herein. Thepresent application claims benefit of U.S. patent application Ser. No.09/425,594 under 35 U.S.C. §120.

FIELD OF THE INVENTION

The present invention relates to controlling vibration in surfaces andin particular relates to a system for controlling and/or dampingvibration of dynamic surfaces.

BACKGROUND OF THE INVENTION

In many industries, such as paper making, food processing, and textiles,or any other industry that processes a web of material, rolls are usedfor various processing functions, and in many instances, the stabilityof the roll is very important. For example, in a paper making assembly,roll vibration may cause variations in the thickness of the productbeing produced. Thus, it is desirable for the rolls to be as stable aspossible and devoid of any imperfections, deflections or variations sothat the paper being formed will be smooth and uniform. In addition toresulting in the production of inferior products, roll vibration mayalso result in damage to the roll itself or the machinery containing theroll. Thus, various attempts have been made to control vibration ofrolls so as to avoid these problems.

One response to this problem has been to lower the rotational speed ofthe rolls in order to avoid or correct vibration-induced defects.

U.S. Pat. No. 5,961,899 to Rossetti et al. discloses a vibration controlapparatus for processing a calendered medium that controls vibrationbetween two or more rolls by controlling vibration induced thicknessvariations in a medium exiting from a nip. The apparatus includes aframe, first and second rolls relative to the frame and a forcegenerator, such as an electromechanical active actuator, aservo-hydraulic actuator, a controllable semi-damper, and ActiveVibration Absorber (AVA), or an Adaptive Tune Vibration Absorber (ATVA),providing canceling forces to control vibration between the first andsecond rolls, thereby controlling vibration induced thickness variationsin the calendered medium. In certain preferred embodiments, theapparatus includes at least one sensor for providing a signal indicatinga vibration condition of at least one of the first and second rolls, anda digital controller for controlling the signal representative of thevibration condition according to a feed-forward-control and providing acontrol signal to a force generator. Vertical and/or lateral vibrationof the rolls may thus be controlled simultaneously. In addition,fundamental vibrational frequencies and their harmonics may becontrolled individually, or in combination.

U.S. Pat. No. 5,447,001 to Nishimura et al. discloses a vibrationcontrol device for buildings. In one preferred embodiment, a buildinghas mounted on its roof a hollow concrete-steel first mast carried ondamping rubber supports. Within the hollow of the first mast, a secondmast is mounted on anti-friction rollers, which roll on a lowcoefficient of friction interior floor of the first mast. The first andsecond masses are interconnected with a single element to vibrate thesemasses with a period of vibration that can be synchronized with thevibration period of the building to attenuate building vibration.

U.S. Pat. No. 5,403,447 to Jarvinen et al discloses a system in a presssection of a paper machine for monitoring and controlling the running ofa press felt. The press felts are guided by rolls having axialdirections that are altered by means of an actuator so as to control therunning of the press felts. The system includes detector devices fordetecting one or more alignment stripes on the felts and oscillationdetectors for detecting oscillation of the press rolls. The system alsoincludes a microprocessor base controller for monitoring signals fed tothe controller from the detectors. The controller analyzes the detectordata in order to detect any felt-induced oscillations. The controlsystem then generates signals for regulating the actuators of the guideroll that guide the running of the felts so that when the oscillationlevels of the press rolls rise above certain limits, the direction ofthe guide roll on the felt that causes the oscillation is turned untilan acceptable level of oscillation and/or a level of oscillation isreached.

U.S. Pat. No. 4,902,384 to Anstotz et al. discloses a wet press havingvibration control. In one preferred embodiment, a wet press of apapermaking machine includes a pair of rolls defining a roll gap throughwhich the paper being treated passes. The felt is guided in a closedloop path by additional rolls, which include a tightening roll. Thetightening roll can be tilted to reduce roll vibrations by tighteningthe felt to set vibratory marks formed in the felt at an angle relativeto the transverse width of the felt and the roll gap. A controllablepositioning device is provided which includes a motor operated by acontroller to automatically vary the tilt angle in response to sensedvibrations.

Vibration is also a problem when using a wet press of a papermakingmachine. In such wet presses, as the felt and paper web to be drainedare simultaneously conducted through a roll gap, water is pressed out ofthe paper web and transferred onto the felt web. The absorbed water isremoved from the felt at another point along its closed loop path by,for example, a suction roll. The pairs of rolls forming the roll gap,along with their guides which engaged roll journals and the elasticallyresilient felt, form a vibrating system with a large number of resonancevibrations that can be excited during operation of the web press.

U.S. Pat. No. 5,785,636 to Bonander discloses a roll having an outersurface made of a fabricated fiber matrix for strengthening andreinforcing the roll to maximize roll stability.

U.S. Pat. No. 4,301,582 to Riihinen discloses a system that removesdeflections from a roll using magnetic forces. The roll has anon-rotating axle with ends having a load imposed thereat and acylindrical shell rotatably supported by bearings on the axle. Amagnetic core is formed in the axle and a plurality of pole shoes arespaced from the shell by an air gap. A plurality of electromagneticwindings, each wound on the core at one of the pole shoes, produce amagnetic compensating force field between the shell and the core forresponding to deflections in the roll.

U.S. Pat. No. 4,357,743 to Hefter, et al., discloses a controlleddeflection roll having a roll shell which is radially movable in atleast one plane in relation to a roll support. Position feelers orsensors are arranged at the ends of the roll shell for detecting one ormore deflections in the roll shell as a function of deviations from apredetermined reference or set point. The position feelers controlregulators operatively associated with pressure or support elementspositioned between the roll support and the roll shell so that the rollshell is maintained in the reference or set position.

U.S. Pat. No. 4,062,097 to Riinhinen discloses a roll having magneticdeflection compensation that may be used in the calender or presssection of a paper machine. The roll has an inner non-rotating axle andan outer shell surrounding and rotatable with respect to the axle, theaxle and the shell having a common axis. The axle includes an innermagnetic structure while the shell includes an outer magnetic structurethat rotates together with the shell. These inner and outer magneticstructures cooperate to provide attraction between the shell and axle onone side of the above axis and repulsion between the shell and axle onthe opposite side of the axis, thereby achieving deflection controland/or compensation.

Other techniques used to reduce the detrimental effects of rollvibration include running process machinery at slower speeds in order toavoid resonance problems, and using back-up roll systems to reducevibration.

Therefore, there is a need to have a vibration control system for adynamic surface that damps or eliminates vibrations in the dynamicsurface. There is also a need for a vibration control system thatenables vibrations to be induced into a dynamic surface for any purposenecessary.

SUMMARY OF THE INVENTION

The present invention addresses the above-identified problems byproviding a system and method for controlling vibration of a dynamicsurface. In its broadest sense, the present invention may be used toeliminate undesirable vibrations from a dynamic surface or to activelyinduce vibrations into the dynamic surface. In preferred embodiments,the present invention may be used to control vibration of a dynamicsurface on any object that rotates including, but not limited to, a rollthat engages a web, a gear, wheels and/or tires. The present inventionmay also be used to reduce or control vibrations in aerodynamic surfacesor one or more surfaces of a loom. In highly preferred embodiments, theinventive system includes at least one piezoelectric actuator incommunication with the dynamic surface of a roll and a mass overlyingthe piezoelectric actuator so that the piezoelectric actuator is betweenthe mass and the dynamic surface for controlling vibration of the rolland/or actively inducing vibration into the roll.

As is well known to those skilled in the art, piezoelectric elements maybe used to covert electrical energy into mechanical energy and viceversa. For nanopositioning, the precise motion that results when anelectric field is applied to a piezoelectric material is of great value.Actuators using this effect have changed the world of precisionpositioning. As used herein, the term “piezoelectric actuator” means apiezoelectric device or element, or any electronic device that operatesin a similar fashion to a piezoelectric element such as an electromagnetor a magnetostatic device.

As set forth herein, the term “dynamic surface” means any surface thatmay change with respect to time, regardless of whether the change occursover 5-10 seconds or over a time period as small as one microsecond.However, as microtechnology improves and microprocessors operate atfaster speeds, it is contemplated that the present invention could beused for dynamic surfaces that change over a period of time as small as1 nanosecond. The present invention may be used for a broad range ofapplications whereby the system components move at various speeds. Forexample, the vibration control system of the present invention can beused when making a paper web moving at approximately 5000 feet/minute,when making textile materials moving at approximately 100-300feet/minute or when making paper maker's clothing (PMC) moving atapproximately 1-30 feet/minute.

In accordance with one aspect of the present invention, there isprovided a system for controlling vibration of a dynamic surface, suchas the exterior surface of a roll. The system preferably includes atleast one sensor in communication with the dynamic surface for measuringvibration of the dynamic surface and generating a feedback signal uponmeasuring vibration. The feedback signal may be proportional to thevelocity, displacement and/or acceleration of the measured vibration.The feedback signal may consist of one or more of these variables. Asused herein, the term “vibration” includes any dynamic surface responseto any force to which the dynamic surface may be subjected includingpressure forces, compressive forces, tensile forces, resonance, thermalaction or other process forces. Moreover, the above-listed vibrationforces may be applied in any direction with respect to the dynamicsurface including directions that are substantially perpendicular to thedynamic surface and directions that are substantially parallel to thedynamic surface. The system also includes at least one piezoelectricactuator in communication with the dynamic surface and at least one massoverlying the at least one piezoelectric actuator so that the at leastpiezoelectric actuator lies between the mass and the dynamic surface.

The system also preferably includes a controller in communication withthe at least one sensor for receiving the feedback signal and sendingthe output signal to the at least one piezoelectric actuator. If thefeedback signal indicates that the dynamic surface is undergoingvibration, the piezoelectric actuator, upon receiving the output signal,applies a counter force between the dynamic surface and the mass uponreceiving the output signal for reducing or controlling vibration of thedynamic surface. The at least one piezoelectric actuator may also beactivated when no vibration is sensed in order to actively inducevibrations into the dynamic surface.

The application of piezoelectric elements to dynamic surfaces, such asthe exterior surface of a roll, resolves vibration problems in a muchmore efficient manner than is available with the vibration controlmethods described above. Piezoelectric actuators can apply forcesindependently in various magnitudes, and in various combinations. Thisis not possible with most if not all of the existing roll controlmethodologies. Piezoelectric actuators are extremely precise, allowingrepeatable nanometer and sub-nanometer movements. In addition,piezoelectric actuators can produce significant amounts of force overrelatively small areas and are capable of moving heavy loads of up toseveral tons. Moreover, because piezoelectric elements derive theirmotion through solid state crystal effects and have no moving parts theresponse time of piezoelectric elements is in the kilohertz range sothat they may be activated at very high frequencies. Finally,piezoelectric elements require very little power and require nomaintenance.

The at least one piezoelectric actuator preferably includes a pluralityof piezoelectric actuators that are provided in contact with the dynamicsurface. The piezoelectric actuators are preferably piezoelectric foilshaving a length of approximately 1 to 5 centimeters, a width ofapproximately 1 to 5 centimeters and a height of less than 1 centimeter.As such, one piezoelectric actuator preferably covers an area ofapproximately 1-25 cm². In other preferred embodiments, piezoelectricactuators of any size and/or dimension may be used. Thus, the presentinvention is not limited to using actuators of the size/type listedabove.

The present invention preferably applies a plurality of piezoelectricactuators in contact with the dynamic surface of a roll so thatrelatively large controlling forces may be applied to the dynamicsurface. Because each piezoelectric actuator can be controlledseparately by the controller, it is possible to impart virtually anytype of vibration or shape in the dynamic surface that is desired,thereby providing for unlimited performance possibilities not availablein prior art technologies.

In one preferred embodiment, the dynamic surface is preferably providedon a roll shell secured over a roll support. The roll shell may be anon-coated or a coated roll. The roll shell is preferably flexible andsubstantially cylindrical, has an interior surface defining an innerdiameter of the roll shell and an exterior surface defining an outerdiameter of the roll shell. The exterior surface of the roll shellpreferably includes the dynamic surface. The sensors and piezoelectricactuators are preferably connected to the interior surface of the rollshell; and one or more masses overlie the piezoelectric actuators sothat the piezoelectric actuators lie between the masses and the interiorsurface of the roll shell. In certain embodiments, the ratio of massesto piezoelectric actuators could be 1:1, however, in other embodimentsthe number of piezoelectric actuators may greatly exceed the number ofmasses or the number of masses may greatly exceed the number ofpiezoelectric actuators. In other embodiments, the sensors andpiezoelectric actuators may be connected to either the inner or exteriorsurface of the roll shell or any combination thereof, so long as themasses overlie the piezoelectric actuators so that the piezoelectricactuators lie between the masses and the dynamic surface. In otherembodiments, the sensors are in communication with, but not in contactwith, the roll shells.

The roll shell preferably has a longitudinal axis and preferably rotatesabout a central axis substantially parallel to the longitudinal axis.The roll shell is desirably mounted on a roll shell support thatsupports rotation of the roll shell about the central axis thereof. Theroll shell support may include an axle mounted to an external supportstructure. The axle may rotate.

In certain embodiments, the counter vibrating force applied by thepiezoelectric actuators generates either a compressive force or atensile force between the mass and the dynamic surface of the rollshell. The compressive and tensile forces are applied through thepiezoelectric actuators and directly to the dynamic surface and thecorresponding mass surfaces. The compressive and tensile forces aregenerally opposed to one another. In other words, the compressive forcescompress the mass and the dynamic surface toward one another while thetensile forces urge the mass and the dynamic surface away from oneanother. The piezoelectric actuators may be aligned to exert compressiveand tensile forces in directions substantially parallel to orsubstantially perpendicular to the longitudinal axis of the shell. Thepiezoelectric actuators may also be aligned to apply compressive andtensile forces to the dynamic surface in a plurality of variousdirections that are neither perpendicular to nor parallel to thelongitudinal axis of the shell.

The vibration control system of the present invention preferablyincludes a plurality of sensors in communication with the shell. Thesensors are designed for detecting and/or measuring the magnitude of thevibration of the dynamic surface of the shell. The sensors arepreferably spaced apart from one another and interspersed between thepiezoelectric actuators. In certain preferred embodiments, thepiezoelectric actuators are aligned in rows over the interior surface ofthe shell and the sensors are interspersed between the piezoelectricactuators. The rows of aligned piezoelectric actuators may extend indirections substantially parallel to or perpendicular to thelongitudinal axis of the shell, or may extend in any number ofdirections between those that are substantially perpendicular and thosethat are substantially parallel to the longitudinal axis of the shell.The ratio of piezoelectric actuators to sensors is preferably about100:1. The sensor may be one of a wide variety of sensors including butnot limited to a piezoelectric element, a strain gauge, a laser used inconjunction with a reflective element, an optical device, a capacitivedevice and/or a magnetic device. In other preferred embodiments, theratio of piezoelectric actuators to sensors will vary. The ratio may be1:1, or the number of sensors may outnumber the number of piezoelectricactuators.

The vibration control system of the present invention also preferablyincludes a controller having a microprocessor and a memory device. Thememory may have stored therein look-up tables, a control strategyalgorithm and/or an adaptive feedback control strategy algorithm. Thecontroller is preferably designed for receiving feedback signals fromthe sensors. The controller then processes the feedback signals todetermine the presence or absence of a vibration. If an undesirablevibration state is detected at one or more regions of the dynamicsurface, the controller transmits output signals to the piezoelectricactuators at those vibrating regions for removing the vibrations. Thecontrol system of the present invention may also be used to activelyinduce vibrations into the dynamic surface.

In certain preferred embodiments, the system for controlling vibrationof a dynamic surface may be utilized for a web support structure locatedbetween two rolls so as to support the web as it passes by the websupport structure. In these particular embodiments, the web supportstructure includes a supporting element having a web support layer. Theweb support layer has a top surface including the dynamic surface and abottom surface remote therefrom. The dynamic surface is designed toengage the web passing thereover, such as a web of partially formedpaper moving over the dynamic surface during a paper forming process.The control system of the present invention may also be used forprocessing textile materials and/or paper maker's clothing felts or anyother process involving web handling. In these particular embodiments,the sensors and the piezoelectric actuators are provided in contact withthe second surface of the web support layer and one or more massesoverlie the piezoelectric actuators so that the piezoelectric actuatorslie between the second surface of the web and the masses. However, inother embodiments, the sensors and piezoelectric actuators may be incontact with either the first surface or the second surface or anycombination thereof, and the masses overlie the piezoelectric actuators.The dynamic surface of the web support layer may be substantially flator have an arcuate section. In certain embodiments, the one or moresensors preferably determine the position of the dynamic surface inrelation to the supporting element for detecting the presence of adeflecting force upon the dynamic surface.

In these embodiments, at least one of the piezoelectric actuators issandwiched between the at least one mass and the interior surface of theshell. In certain applications, there is a need to operate rolls at aspeed that coincides with the resonance of the roll. When operated at ornear resonance, a roll's dynamic response may cause detrimental effectson the roll itself, the machinery containing the roll and the processthat the roll is completing. Using piezoelectric devices mounted betweenthe roll (or other machine members) and a mass, and having thepiezoelectric actuator connected to and controlled by a properlydesigned control device, vibrations in the dynamic surface of the rollcan be reduced and/or controlled, thereby eliminating or reducingdetrimental effects. Similarly, vibrations can be induced into rolls orother machine members for any purposes necessary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic side view of a prior art roll and mating rollengaging a web at a nip.

FIG. 1B is a schematic side view of another prior art roll engaging aweb.

FIG. 2A is a sectional view of the prior art roll of FIG. 1A taken alonglines IIA—IIA.

FIG. 2B is a sectional view of the prior art roll of FIG. 1B taken alonglines IIB—IIB.

FIG. 3A shows a simplified view of the prior art roll of FIG. 1A duringrotation of the roll.

FIG. 3B shows a simplified view of the prior art roll of FIG. 1B duringoperation of the roll.

FIG. 4A is a schematic cross-sectional view of a roll including a systemfor controlling vibration of the roll, in accordance with certainpreferred embodiments of the present invention.

FIG. 4B is a fragmentary schematic cross-sectional view of a roll, inaccordance with further preferred embodiments of the present invention.

FIG. 4C is a fragmentary schematic cross-sectional view of a roll, inaccordance with still further preferred embodiments of the presentinvention.

FIG. 4D is a fragmentary schematic cross-sectional view of a roll, inaccordance with yet further preferred embodiments of the presentinvention.

FIG. 5 is a fragmentary view of a the roll of FIG. 4A taken along linesV—V including a plurality of sensors in contact with the dynamic surfaceof the roll and a plurality of masses overlying piezoelectric actuators,in accordance with certain preferred embodiments of the presentinvention.

FIG. 6 shows a fragmentary view, on an enlarged scale, of the dynamicsurface of the roll shown in FIG. 5.

FIG. 7 shows the roll shown in FIG. 4A during operation of the roll.

FIG. 8A is a schematic cross-sectional view of a non-coated rollincluding a system for controlling vibration of the roll, in accordancewith further preferred embodiments of the present invention.

FIG. 8B is a schematic side view of a coated roll including a system forcontrolling vibration of the roll, in accordance with still furtherpreferred embodiments of the present invention.

FIG. 9 shows a schematic side view of a system for controlling vibrationof a dynamic surface, in accordance with further preferred embodimentsof the present invention.

FIG. 10A is a sectional view taken along lines X—X of FIG. 9, showingthe dynamic surface of a web support layer.

FIG. 10B shows a sectional view of a system for controlling deflectionof a dynamic surface including a mating roll for creating nip pressure,in accordance with further preferred embodiments of the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1A-3B show prior art rolls. Referring to FIG. 1A, the roll 20 is anon-coated roll including an axle 22 loaded at its ends. A non-coatedroll generally includes rolls having metal tubes, such as a steel rollor tube. In contrast, a coated roll is understood to be a roll that iscoated with a layer of flexible material such as rubber, fabric orcloth. The loading forces F are shown in FIG. 1. The forces F, togetherwith the weight of the roll, provide the required nip pressure at thenip N formed by the interface of roll 20 and a mating roll 24. Theforces shown in FIG. 1 and described above are dependent upon theposition of the roll 20 relative to the mating roll 24. For example,these forces would change if the roll 20 were under the mating roll 24(i.e., under the nip). The roll 20 includes a roll shell 26 that issecured about axle 22 via bearings 28. The roll shell has an interiorsurface 30 and an exterior surface 32. The longitudinal axis orcenterline of the axle 22 is indicated by A—A.

FIG. 1B shows another prior art non-coated roll 20′ that does not havean axle extending therethrough as shown in FIG. 1A. The roll 20′includes a roll shell 26′ having an interior surface 30′ and an exteriorsurface 32′. The roll 20′ includes supports 22A′ and 22B′ that supportthe interior surface 30′ of the roll shell 26′ as the roll shell rotatesabout a longitudinal axis A′—A′. The supports 22A′ and 22B′ includesextensions 27′ supported by bearings 28′.

FIG. 2A shows a cross sectional view of the roll 20 and the mating roll24 of FIG. 1A taken along line IIA—IIA of FIG. 1A. The roll 20 andmating roll 24 are designed for allowing a web 34 to pass therebetweenat the nip N. Mating rolls facilitate the development of nip pressuresbetween two rolls, thereby minimizing deflection of one or more rolls.Mating rolls, such as mating roll 24, may also be used as backup orsupport rolls. The roll 20 and the mating roll 24 may typically beincorporated into any assembly that processes a web of material such asa paper making assembly, a textile making assembly, a paper maker'sclothing making assembly, a printing assembly, a metal rolling assembly,an embossing assembly or a calendaring assembly.

FIG. 2B shows a cross-sectional view of the roll 20′ of FIG. 1B takenalong line IIB—IIB of FIG. 1B. The roll 20′ of FIG. 2B is a singularroll that is not in contact with a mating roll for creating nippressure.

FIG. 3A shows a simplified view of the roll 20 of FIGS. 1A and 2A whenthe roll is vibrating. The mating roll 24 may also vibrate as indicatedby the dashed lines. The vibration of the roll 20 may be the result ofvibrating forces applied to the exterior surface 32 of the roll by a web(not shown), or by the resonance frequencies of the rolls or otherexciting energies such as vibrational energy transmitted from any otherpart of a machine that causes a roll to go into resonance or drives aroll into a vibrating state. FIG. 3B shows a simplified view of the roll20 of FIGS. 1B and 2B when the roll is vibrating. The roll vibrationshown in FIGS. 3A and 3B can have detrimental effects on the rolls, themachinery containing the rolls or the products being produced using therolls. The present invention is directed towards a control system thatboth detects roll vibration anywhere on a roll and actively corrects thecondition for rapidly and efficiently returning the roll to anon-vibrating state. In certain embodiments, it may be preferable todetect and/or correct roll vibration only at the portion of the roll atthe nip. To a broader extent, the present invention is directed towardproviding a control system for a dynamic surface for detecting theoccurrence of a vibration in a dynamic surface, measuring the velocity,acceleration or displacement of the vibration, and then operatingactuators to return the dynamic surface to a non-vibrating condition.

FIG. 4A shows a deflection control system 100 for a roll 102 inaccordance with certain preferred embodiments of the present invention.The roll 102 includes an axle 104 having bearings 106 for supporting aroll shell 108. The roll shown in FIG. 4A is commonly referred to as anon-coated roll. A non-coated roll is typically made by providing a rollshell, such as a solid steel shell, that supplies the main support forthe roll. The roll shell 108 has a longitudinal axis that issubstantially parallel to the longitudinal axis B—B of axle 104. Theroll shell 108 is generally cylindrical or tubular and includes an innersurface 110 defining an inner diameter and an exterior surface 112defining an outer diameter. The outer diameter is (O.D.) of the roll 102is defined by the exterior surface 112 of roll shell 108.

The vibration control system also includes a plurality of sensors 114and a plurality of piezoelectric actuators 116 connected to the interiorsurface 110 of the roll shell 108. The sensors 114 and piezoelectricactuators 116 are in signal sending and receiving communication with acontroller 118 via conductive traces 120 extending between the sensors114 and piezoelectric actuators 116, and the controller 118. For clarityof illustration, FIG. 4A shows only one sensor 114 and one piezoelectricactuator 116 connected to controller 118, however, it should beunderstood that all of the sensors and actuators are preferably insignal sending and receiving communication with the controller. Thecontrol system also includes a mass 125 overlying each piezoelectricactuator 116. As a result, each piezoelectric actuator is positionedbetween the inner surface 110 of the roll shell 108 and one of themasses 125 overlying the piezoelectric actuators.

In the particular embodiment shown in FIG. 4A, the controller 118 islocated within the roll 102 for rotating simultaneously with the roll,the sensors 114, the piezoelectric actuators 116 and the masses 125.Power for the controller may be provided from a stationary power source122 through a power line 123 that extends through axle 104. The energyis transmitted from the stationary power source to the rotatingcontroller via a connection mechanism, such as a slip ring, that willnot twist the power line 123 as the roll rotates. The controller 118preferably includes a microprocessor 124 and a memory device 126 forstoring a deflection control strategy or data related to preferredoperating conditions for the roll 102 and roll shell 108. The controller118 preferably uses one or more software applications stored therein,the software applications being capable of receiving feedback signalsfrom the sensors 114, comparing the feedback signals with data stored inthe memory device 126 and generating a series of output signals fortransmission to the piezoelectric actuators 116. Upon receiving theoutput signals, the piezoelectric actuators are actuated for drawing themasses and the dynamic surface toward one another or forcing the massesand the dynamic surface away from one another so as to remove vibrationsfrom the roll shell 108, as will be described in more detail below.

In operation, a moving web (not shown) passes through a nip N created byroll 102 and mating roll 130. The roll 102 and mating roll 130 are shownin a generally horizontal orientation, however, the vibration controlsystem of the present invention is also intended for use when the rolls102, 130 have a substantially vertical orientation or any othergeometric orientation with respect to the ground or one another. Forclarity of illustration, FIG. 4A shows two rolls: roll 102 and matingroll 130. However, the present invention may also be used forcontrolling vibrations in systems having three or more rolls in contactwith one another including a calendar stack of rolls whereby at leastone of the rolls in the stack has two or more nip surfaces.

FIG. 4B shows a fragmentary view of a roll having a vibration controlsystem in accordance with further preferred embodiments of the presentinvention. The FIG. 4B embodiment is substantially similar to theembodiment shown in FIG. 4A, however, the FIG. 4B embodiment includes acoated roll 102′ having a roll shell 108′. The roll shell 108′ includesa flexible coating 108A′ overlying a structural support member 108B′.The flexible coating preferably includes a flexible material such as anelastomer (e.g. rubber) or cloth. When the flexible material is anelastomer, the structural support member 108B′ is preferably a solidtube, such as a steel tube. The outer diameter of the coated roll 102′is defined by the exterior surface 112′ of the flexible coating 108A′.The system includes a plurality of piezoelectric actuators 116′ andsensors 114′ overlying the inner surface 110′ of the roll shell 108B′and masses 125′ overlying the piezoelectric actuators.

FIG. 4C shows another embodiment of the present invention having thesensors 114″ and piezoelectric actuators 116″ on the outer diameter 112″of the roll 102″. The roll 102″ is a coated roll including a roll shell108″ including a flexible coating 108A″ overlying a structural supportmember 108B″. The sensors 114″ and piezoelectric actuators 116″ are onthe exterior surface 112″ of the flexible coating 108A″. Masses 125″ areprovided over the piezoelectric actuators 116″ so that the piezoelectricactuators 116″ are sandwiched between the exterior surface 112″ of theflexible coating 108A″ and the masses 125″. In further embodiments, theroll may be a non-coated roll and the sensors, actuators and masses areprovided on the exterior surface of the roll shell (i.e., the exteriorsurface of the structural support member).

FIG. 4D shows a fragmentary view of a roll having a vibration controlsystem in accordance with further preferred embodiments of the presentinvention. In FIG. 4D the ratio of masses 125′″ to piezoelectricactuators 116′″ may be 1:1, or the number of masses 125′″ may exceed orbe less than the number of piezoelectric actuators 116′″. The left sideof the roll has two masses 125A′″ and 125B′″ overlying one piezoelectricactuator. In the center of the roll, one mass 125C′″ overlies threepiezoelectric actuators. On the right side of the roll, the ratio ofmasses to actuators is 1:1 as three masses 125D′″, 125E′″ and 125F′″overlie three separate piezoelectric actuators.

Although the present specification provides a detailed description ofthe vibration control system of the present invention when describingthe roll 102 embodiment shown in FIG. 4A, the present invention isequally applicable to the coated roll 102′ embodiment shown in FIG. 4B,the roll 102″ embodiment shown in FIG. 4C, or any other type of dynamicsurface.

FIG. 5 shows a fragmentary view of FIG. 4A, taken along lines V—V,showing sensors 114 and masses 125/piezoelectric actuators 116 connectedto the inner surface 110 of the roll shell 108. The masses 125 overliethe piezoelectric actuators which are not shown. The piezoelectricactuators and the masses overlying the piezoelectric actuators arepreferably aligned in rows C, D, E, F, G, H and I that extendsubstantially parallel to the longitudinal axis B—B of the roll shell108. Each mass is preferably in registration with one of thepiezoelectric actuators. Each mass 125 preferably has a length ofapproximately 1 to 5 centimeters, a width of approximately 1 to 5centimeters, and a height of less than one centimeter. Thus, each mass125 generally covers an area of approximately 1-25 cm². Thepiezoelectric actuators generally cover the same area as the masses. Thesensors 114 are interspersed between the masses 125 and are preferablyspaced so that the controller is able to monitor the entire dynamicsurface of the roll. As mentioned above, the sensors are designed fordetecting the presence of vibration of the dynamic surface of the rollshell 108.

The number of piezoelectric actuators 116 and masses 125 generallyoutnumber the number of sensors 114 by a significant amount. In onepreferred embodiment, the ratio of masses and piezoelectric actuators tosensors is approximately 100:1. Preferred sensors include piezoelectricelements, strain gauges, a laser and reflective element sub-assembly, anoptical device, a capacitive device, and/or a magnetic device. In thepreferred embodiment shown in FIGS. 4A and 5, the sensors arepiezoelectric elements capable of detecting a vibration of the dynamicsurface of the roll. Such vibration will strain the piezoelectric sensorto stretch or compress. The piezoelectric sensor will then transform thephysical movement into an electric feedback signal, whereby themagnitude of the electric feedback signal may be proportional to themagnitude of the physical movement of the sensor. The electric feedbacksignal is sent to the controller. The electric signal may be either anelectric voltage signal or a current signal.

FIG. 6 shows an enlarged fragmentary view of rows D, E and F of FIG. 5.Each row includes masses 125 overlying piezoelectric actuators (notshown) with sensors 114 interspersed between the masses andpiezoelectric actuators. The sensors 114 preferably monitor a specificregion of the roll shell 108 to detect whether that region is subjectedto vibration. Each sensor 114 operates independently of the othersensors. For example, sensor 114 F in row F may detect a vibration whilesensor 114E of row E detects no vibration. The piezoelectric actuatorsmay also operate independently of one another. For example,piezoelectric actuator 116F may apply a counter vibrating force to theroll shell while piezoelectric actuator 116E is not actuated and appliesno counter vibrating force to the roll shell. Moreover, piezoelectricactuators adjacent one another may apply counter vibrating forces havingdifferent magnitudes; e.g. the piezoelectric actuator underlying mass125E applies a counter vibrating force having a greater magnitude thatthe force applied by the piezoelectric actuator underlying mass 125E′.The actual magnitude of the counter vibrating force applied by any onepiezoelectric actuator is typically proportional to the magnitude of theelectric signal received from the controller 118 (FIG. 4). Although themasses 125 and the actuators 116 underlying the masses are depicted inrows, the present invention includes embodiments where the masses andactuators are arranged randomly or in a pattern. The sensors 114 mayalso be arranged in a pattern or randomly.

Referring to FIGS. 4A and 6, during operation or rotation of the roll102, the region of the roll shell 108 overlying row D may be in contactwith a moving web while regions of the roll shell overlying rows E and Fare not in contact with the web. As a result, the moving web vibratesthe roll shell overlying row D while rows E and F are not vibrating.Thus, the sensors 114D in row D will detect vibration while the sensors114E and 114F of respective rows E and F will not detect vibration. Inresponse, output signals sent from the controller to piezoelectricactuators of row D will physically move those piezoelectric actuatorsfor damping vibration of the dynamic surface of the roll shell 108overlying actuators 116D. However, no output signals will be sent to thepiezoelectric actuators 116E and 116F in rows E and F. As such,piezoelectric actuators will only be activated by output signals whennecessary to control and/or damp vibration of the roll shell or when itis desirable to actively vibrate the dynamic surface of the roll shell.The force applied by each actuator in any one row may vary. For example,the actuators in the center of a row may apply more force than theactuators adjacent a journal. In addition, in any one row, the actuatorsadjacent one journal may provide more force than the actuators adjacentan opposed journal.

FIGS. 7 and 8 show the roll 102 of FIG. 4A before activation of thevibration control system of the present invention. During operation ofthe roll, a web 128 (not shown in FIG. 7) passes between the roll 102and mating roll 130. The rotational speed of the roll 102 is dependentupon a number of factors including the speed of the web passing betweenroll 102 and mating roll 130 and the outer diameter of the roll.Referring to FIG. 8, in response to a number of vibrating forces,including the high rate of rotation of the roll (e.g., 5000revolutions/minute) web tension, nip pressure and gravity, the roll 102and the roll shell 108 vibrate. As set forth above, vibration of theroll is undesirable because it will have an adverse effect on thematerial 128 (e.g., a web) passing between the roll 102 and the matingroll 130.

Referring to FIG. 7, during operation the sensors 114 are activated fordetecting vibration of the dynamic surface of the roll 102 and to sendfeedback signals back to the controller (FIG. 4) upon sensing vibration.Upon receiving feedback signals from the sensors, the controller willdetermine the magnitude of the vibration. The controller will thencalculate output signals to be sent to each of the piezoelectricactuators 116 connected to the roll shell. The magnitude of the outputsignals sent to the individual piezoelectric actuators may vary becausethe amount of damping force or attenuating force required at eachparticular region of the roll may vary. Upon receiving the outputsignals from the controller, the piezoelectric actuators 116 will exerttensile and/or compressions forces on the dynamic surface of the rollfor damping and/or controlling vibration of the dynamic surface. Incertain embodiments, one or more piezoelectric actuators may saturate or“max out”; i.e. a condition where the piezoelectric actuator is exertinga maximum force and this maximum force is not enough to completely dampor control a localized vibration in the dynamic surface. In theseinstances, piezoelectric actuators located outside the area of thevibration may be actuated to assist the “maxed out” piezoelectricactuators.

FIG. 8A shows a vibration control system 200 for a non-coated roll 202in accordance with further preferred embodiments of the presentinvention. The roll 202 includes a roll shell 208 having first andsecond ends 215A and 215B. The system includes first and second supports217A and 217B for supporting the first and second ends 215A and 215B ofthe roll shell 208. The supports 217A and 217B are connected with theinterior surface 210 of the roll shell 208 for supporting rotation ofthe roll 202. The supports 217A and 217B extend beyond the ends 215A and215B of the roll shell 208 to bearings 206 so that the roll 202 mayrotate about longitudinal axis C—C. The roll 202 includes a controller218 for controlling vibration of the roll shell 208. The controller 218is in communication with sensors 214 and piezoelectric actuators 216 viatraces 220. FIG. 8A shows only one sensor 214 and one piezoelectricactuator 216 connected to controller 218, however, it should beunderstood that all of the sensors and actuators are preferably insignal sending and receiving communication with the controller. Masses225 overlie the piezoelectric actuators 216 so that the piezoelectricactuators 216 lie between the inner surface 210 of the roll shell 208and the masses 225. The controller 218 is preferably located within rollshell 208 for rotating simultaneously with the roll shell, the sensors214 and the piezoelectric actuators 216. Power for the controller 218may be provided from a power source 222 through a power line 223 thatextends through one of the structural members 217. The controller 118operates in a manner that is substantially similar to that describedabove in regards to FIG. 4A.

FIG. 8B shows another embodiment of the present invention that issubstantially similar to the FIG. 8A embodiment, however, the FIG. 8Bembodiment includes a coated roll 202′. The coated roll 202′ includes aroll shell 208′ having a flexible coating 208A′ surrounding structuralsupport member 208B′. The outer diameter of the coated roll 202′ isdefined by the exterior surface 212′ of the flexible coating 208A′. Boththe non-coated roll 202 of FIG. 8A and the coated roll 202′ of FIG. 8Bare dynamically flexible and include dynamic surfaces as that term isdefined herein. As a result, the non-coated and coated rolls disclosedherein may deflect and/or vibrate during operation.

FIGS. 9 and10A show a deflection control system in accordance withfurther preferred embodiments of the present invention. Referring toFIG. 9, a web support element 300 is provided between two rolls 302 and304. The web support element 300 supports a web 306 moving between firstroll 302 and second roll 304. Referring to FIG. 10A, the web supportelement 300 includes a web support layer 308 having a first surface 310for engaging the web 306 and a second surface 312 remote therefrom. Thesecond surface 312 of the web support layer 308 includes sensors 314 andpiezoelectric actuators 316 connected thereto. Masses 325 overlie thepiezoelectric actuators for damping vibrational forces on the websupport layer 308.

FIG. 10B shows another embodiment, similar to the embodiment of FIG.10A, including a mating roll 330′, whereby a web 306′ passes between themating roll and the web support layer 308′.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. For example, the present invention may beincorporated into the wing of an airplane or onto a surface of a machinefor controlling vibration of these surfaces. It is therefore to beunderstood that numerous modifications may be made to the illustrativeembodiments and that other arrangements may be devised without departingfrom the spirit and scope of the present invention as defined by theappended claims.

What is claimed is:
 1. A system for controlling vibration of a dynamicsurface comprising: at least one sensor in communication with saiddynamic surface for measuring vibration of said dynamic surface andgenerating a feedback signal upon measuring vibration; at least onepiezoelectric actuator in communication with said dynamic surface; atleast one mass overlying said at least one piezoelectric actuator,wherein said at least one piezoelectric actuator lies between said massand said dynamic surface; a controller in communication with said atleast one sensor for receiving the feedback signal, generating an outputsignal in response to the feedback signal and sending the output signalto said at least one piezoelectric actuator, wherein said piezoelectricactuator applies a counter force between said dynamic surface and saidmass upon receiving the output signal for damping or controllingvibration of said dynamic surface.
 2. The system as claimed in claim 1,further comprising a roll shell including said dynamic surface.
 3. Thesystem as claimed in claim 2, wherein said roll shell has an interiorsurface and an exterior surface.
 4. The system as claimed in claim 3,wherein the exterior surface of said roll shell includes the dynamicsurface.
 5. The system as claimed in claim 3, wherein the interiorsurface of said roll shell includes the dynamic surface.
 6. The systemas claimed in claim 1, wherein said at least one sensor is connected tothe dynamic surface.
 7. The system as claimed in claim 3, wherein saidat least one piezoelectric actuator is connected to the dynamic surface.8. The system as claimed in claim 3, wherein said at least one sensor isconnected to the interior surface of said roll shell.
 9. The system asclaimed in claim 3, wherein said at least one sensor is connected to theexterior surface of said roll shell.
 10. The system as claimed in claim3, wherein said at least one piezoelectric actuator is connected to theinterior surface of said roll shell.
 11. The system as claimed in claim3, wherein said at least one piezoelectric actuator is connected to theexterior surface of said roll shell.
 12. The system as claimed in claim2, wherein said roll shell is rotatable about a central axis.
 13. Thesystem as claimed in claim 12, wherein said roll shell has alongitudinal axis substantially parallel to the central axis.
 14. Thesystem as claimed in claim 2, wherein said roll shell is substantiallycylindrically shaped.
 15. The system as claimed in claim 12, furthercomprising a support member for supporting rotation of said roll shellabout said central axis.
 16. The system as claimed in claim 15, whereinsaid support member includes an axle extending in a directionsubstantially parallel to the longitudinal axis of said roll shell. 17.The system as claimed in claim 15, wherein said roll shell has first andsecond ends and wherein said roll shell support includes first andsecond structural members supporting the interior surface of said rollsupport at the first and second ends thereof.
 18. The system as claimedin claim 17, wherein said roll shell support includes bearings locatedexternal to said roll shell for engaging said first and secondstructural members and supporting rotation of said roll shell.
 19. Thesystem as claimed in claim 1, further comprising a noncoated rollincluding said dynamic surface.
 20. The system as claimed in claim 1,further comprising a coated roll including said dynamic surface.
 21. Thesystem as claimed in claim 13, wherein the counter force applied by saidat least one piezoelectric actuator generates a compressive forcebetween the dynamic surface of said roll shell and said mass in adirection substantially perpendicular to the central axis of said rollshell.
 22. The system as claimed in claim 13, wherein the counter forceapplied by said at least one piezoelectric actuator generates a tensileforce between the dynamic surface of said roll shell and said mass in adirection substantially perpendicular to the central axis of said rollshell.
 23. The system as claimed in claim 13, wherein the counter forceapplied by said at least one piezoelectric actuator generatescompressive and tensile forces between the dynamic surface of said rollshell and said mass in directions substantially perpendicular to thecentral axis of said roll shell.
 24. The system as claimed in claim 13,wherein the counter force applied by said at least one piezoelectricactuator generates compressive and tensile forces between the dynamicsurface of said roll shell and said mass in directions substantiallynon-parallel to the central axis of said roll shell.
 25. The system asclaimed in claim 1, wherein said at least one sensor measures thevelocity, displacement or acceleration of the vibration on said dynamicsurface.
 26. The system as claimed in claim 25, wherein the counterforce applied by said at least one piezoelectric actuator has amagnitude proportional to the magnitude of the feedback signal.
 27. Thesystem as claimed in claim 1, wherein said at least one sensor includesa plurality of sensors.
 28. The system as claimed in claim 1, whereinsaid at least one sensor includes a vibration transducer.
 29. The systemas claimed in claim 1, wherein said at least one piezoelectric actuatorincludes a plurality of piezoelectric elements.
 30. The system asclaimed in claim 3, wherein said at least one sensor includes aplurality of sensors and said at least one piezoelectric actuatorincludes a plurality of piezoelectric elements.
 31. The system asclaimed in claim 3, wherein said sensors and said piezoelectricactuators are in contact with the interior surface of said roll shell.32. The system as claimed in claim 31, wherein said at least one massincludes a plurality of masses, each said mass being mounted atop one ofsaid piezoelectric actuators.
 33. The system as claimed in claim 30,wherein said sensors and said piezoelectric actuators are in contactwith the exterior surface of said roll shell.
 34. The system as claimedin claim 32, wherein the ratio of said piezoelectric actuators to saidmasses are 1:1.
 35. The system as claimed in claim 30, wherein saidsensors are interspersed between said piezoelectric actuators.
 36. Thesystem as claimed in claim 30, wherein the ratio of said piezoelectricactuators to said sensors are approximately 100:1.
 37. The system asclaimed in claim 1, wherein said at least one piezoelectric actuator hasa length of approximately 1-5 cm., a width of approximately 1-5 cm., anda height of less than 1 cm.
 38. The system as claimed in claim 1,wherein said at least one piezoelectric actuator covers an area ofapproximately 1-25 cm².
 39. A system for applying a vibrational force toa dynamic surface comprising: at least one piezoelectric actuator incommunication with said dynamic surface; at least one mass overlyingsaid at least one piezoelectric actuator, wherein said at least onepiezoelectric actuator lies between said at least one mass and saiddynamic surface; a controller in communication with said at least onepiezoelectric actuator for transmitting an output signal to said atleast one piezoelectric actuator, wherein upon receiving the outputsignal said at least one piezoelectric actuator is activated forapplying a compressive or tensile force between said dynamic surface andsaid mass.
 40. The system as claimed in claim 39, further comprising atleast one sensor in communication with said dynamic surface formeasuring vibration on said dynamic surface and generating a feedbacksignal upon sensing vibration.
 41. The system as claimed in claim 40,wherein the feedback signal is proportional to the magnitude of themeasured vibration.